1. Field of the Invention
The present invention relates to a short dwell coater apparatus for the application of coating material to a web which is supported by a backing member. More particularly, the present invention relates to a short dwell coater apparatus having means for reducing a vortex generated within the application zone of the apparatus.
2. Information Disclosure Statement
Short dwell coaters permit the application of pressurized coating material to a web movably supported on a backing roll.
Typically, a short dwell coater includes an application zone having an open face towards the web so that the coating material is applied to the web with excess coating material being removed from the web by a blade defining the downstream end of the application zone.
Short dwell coaters permit the application of a relatively thin layer of coating material to a web because the dwell time of the web moving past the application zone is relatively short. Therefore, the coating material has little time to absorb deeply into the surface of the web to be coated.
The aforementioned short dwell coater also has the advantage that by applying a relatively thin coating to the web, economy of coating material is achieved.
However, during high speed application of coating material utilizing a short dwell coater apparatus, it has been observed that machine directional streaks appear on the surface of the coated web.
More particularly, it is thought that such streaking is as a result of air passing between the web and the apparatus becoming entrapped within the application zone and such air forming a vortex within the application zone due to the momentum of the web moving past the application zone.
The present invention seeks to overcome the aforementioned problem by the provision of a movable flow divider located within the application zone for dampening the aforementioned vortex and for reducing the size thereof.
Therefore, it is a primary objective of the present invention to provide a short dwell coater apparatus which overcomes the aforementioned inadequacies of the prior art devices and which makes a considerable contribution to the art of short dwell coating.
Another object of the present invention is the provision of a short dwell coater apparatus having a movable flow divider which is supported by a housing and which extends into the application zone. The divider has a downstream end which is movably disposed in the vicinity of a blade for reducing the size of the flow vortex generated within the application zone.
Other objects and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter, taken in conjunction with the annexed drawings.